On Mon, 14 Nov 2022 at 19:14, PierreGondois <pierre.gond...@arm.com> wrote:
>
> From: Pierre Gondois <pierre.gond...@arm.com>
>
> BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=4151
>
> PcdCpuRngSupportedAlgorithm is set to the Zero Guid for KvmTool
> since it is not possible to predict which algorithm will be
> implemented for Arm's FEAT_RNG in the host. Current handling is:
> - skipping the Zero Guid, which should not happen to handle
> KvmTool's case,
> - triggering an ASSERT if no algorithm was found. However having
> no Rng algorithm is a valid case,
>
> Correctly handle the Zero Guid case and replace the ASSERT by a
> warning message when no Rng algorithm is found.
> Also simplify the selection of the Rng algorithm when the default
> one is selected by just picking up the first element of
> mAvailableAlgoArray.
>
Can you explain a bit more please
What is supposed to happen?
What happens instead?
Why is this patch the correct way to address this issue?
> Reported-by: Sami Mujawar <sami.muja...@arm.com>
> Signed-off-by: Pierre Gondois <pierre.gond...@arm.com>
> ---
> .../RandomNumberGenerator/RngDxe/ArmRngDxe.c | 15 +++------------
> SecurityPkg/RandomNumberGenerator/RngDxe/RngDxe.c | 8 +++++++-
> 2 files changed, 10 insertions(+), 13 deletions(-)
>
> diff --git a/SecurityPkg/RandomNumberGenerator/RngDxe/ArmRngDxe.c
> b/SecurityPkg/RandomNumberGenerator/RngDxe/ArmRngDxe.c
> index 5ba319899ce9..722d53386373 100644
> --- a/SecurityPkg/RandomNumberGenerator/RngDxe/ArmRngDxe.c
> +++ b/SecurityPkg/RandomNumberGenerator/RngDxe/ArmRngDxe.c
> @@ -76,7 +76,6 @@ RngGetRNG (
> )
> {
> EFI_STATUS Status;
> - UINTN Index;
>
> if ((This == NULL) || (RNGValueLength == 0) || (RNGValue == NULL)) {
> return EFI_INVALID_PARAMETER;
> @@ -86,21 +85,13 @@ RngGetRNG (
> //
> // Use the default RNG algorithm if RNGAlgorithm is NULL.
> //
> - for (Index = 0; Index < mAvailableAlgoArrayCount; Index++) {
> - if (!IsZeroGuid (&mAvailableAlgoArray[Index])) {
> - RNGAlgorithm = &mAvailableAlgoArray[Index];
> - goto FoundAlgo;
> - }
> - }
> -
> - if (Index == mAvailableAlgoArrayCount) {
> - // No algorithm available.
> - ASSERT (Index != mAvailableAlgoArrayCount);
> + if (mAvailableAlgoArrayCount != 0) {
> + RNGAlgorithm = &mAvailableAlgoArray[0];
> + } else {
> return EFI_DEVICE_ERROR;
> }
> }
>
> -FoundAlgo:
> if (CompareGuid (RNGAlgorithm, PcdGetPtr (PcdCpuRngSupportedAlgorithm))) {
> Status = RngGetBytes (RNGValueLength, RNGValue);
> return Status;
> diff --git a/SecurityPkg/RandomNumberGenerator/RngDxe/RngDxe.c
> b/SecurityPkg/RandomNumberGenerator/RngDxe/RngDxe.c
> index 421abb52b8bf..403b31b73609 100644
> --- a/SecurityPkg/RandomNumberGenerator/RngDxe/RngDxe.c
> +++ b/SecurityPkg/RandomNumberGenerator/RngDxe/RngDxe.c
> @@ -21,6 +21,7 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
>
> #include <Library/BaseLib.h>
> #include <Library/BaseMemoryLib.h>
> +#include <Library/DebugLib.h>
> #include <Library/UefiBootServicesTableLib.h>
> #include <Library/RngLib.h>
> #include <Protocol/Rng.h>
> @@ -80,7 +81,12 @@ RngDriverEntry (
> //
> // Get the list of available algorithm.
> //
> - return GetAvailableAlgorithms ();
> + Status = GetAvailableAlgorithms ();
> + if (mAvailableAlgoArrayCount == 0) {
> + DEBUG ((DEBUG_WARN, "No Rng algorithm found in RngDxe.\n"));
> + }
> +
> + return Status;
> }
>
> /**
> --
> 2.25.1
>
>
>
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